boot(app, [options], [callback])

Initialize an application from an options object or
a set of JSON and JavaScript files.

NOTE: This module is primarily intended for use with LoopBack 2.0.
It does work with LoopBack 1.x applications, but
none of the LoopBack 1.x examples or generated code (scaffolding) use it.

This function takes an optional argument that is either a string
or an object.

If the argument is a string, then it sets the application root directory
based on the string value. Then it:

Creates DataSources from the datasources.json file in the application
root directory.

Configures Models from the model-config.json file in the application
root directory.

Configures the LoopBack Application object from the config.json file
in the application root directory. These properties can be accessed
using app.get('propname').

If the argument is an object, then it looks for models, dataSources,
'config', modelsRootDir, dsRootDir, appConfigRootDir and appRootDir
properties of the object.

If the object has no appRootDir property then it sets the current working
directory as the application root directory.

The execution environment, {env}, is established from, in order,

options.env

process.env.NODE_ENV,

the literal development.

Then it:

Creates DataSources from the options.dataSources object, if provided;
otherwise, it searches for the files

datasources.json,

datasources.local.js or datasources.local.json (only one),

datasources.{env}.js or datasources.{env}.json (only one)

in the directory designated by 'options.dsRootDir', if present, or the
application root directory. It merges the data source definitions from
the files found.

Creates Models from the options.models object, if provided;
otherwise, it searches for the files

model-config.json,

model-config.local.js or model-config.local.json (only one),

model-config.{env}.js or model-config.{env}.json (only one)

in the directory designated by 'options.modelsRootDir', if present, or
the application root directory. It merges the model definitions from the
files found.

Configures the Application object from the options.config object,
if provided;
otherwise, it searches for the files

config.json,

config.local.js or config.local.json (only one),

config.{env}.js or config.{env}.json (only one)

in the directory designated by 'options.appConfigRootDir', if present, or
the application root directory. It merges the properties from the files
found.

In both cases, the function loads JavaScript files in the
/boot subdirectory of the application root directory with require().

NOTE: The version 2.0 of loopback-boot changed the way how models
are created. The model-config.json file contains only configuration
options like dataSource and extra relations. To define a model,
create a per-model JSON file in models/ directory.

NOTE: Mixing bootLoopBackApp(app, bootConfig) and
app.model(name, modelConfig) in multiple
files may result in models being undefined due to race conditions.
To avoid this when using bootLoopBackApp() make sure all models are passed
as part of the models definition.

Throws an error if the config object is not valid or if boot fails.

Arguments

Name

Type

Description

app

LoopBack application created by loopback().

options

String or Object

Boot options; If String, this is the application root directory; if object, has below properties.

[callback]

Function

Callback function.

options

Name

Type

Description

[appRootDir]

String

Directory to use when loading JSON and JavaScript files.
Defaults to the current directory (process.cwd()).

[appConfigRootDir]

String

Directory to use when loading config.json. Defaults to appRootDir.

[models]

Object

Object containing Model configurations.

[modelDefinitions]

Array

List of model definitions to use. When options.modelDefinitions is provided, loopback-boot does not
search filesystem and use only the models provided in this argument.

[dataSources]

Object

Object containing DataSource definitions.

[modelsRootDir]

String

Directory to use when loading model-config.json. Defaults to appRootDir.

[dsRootDir]

String

Directory to use when loading datasources.json. Defaults to appRootDir.

[middlewareRootDir]

String

Directory to use when loading middleware.json. Defaults to appRootDir.

[componentRootDir]

String

Directory to use when loading component-config.json. Defaults to appRootDir.

[env]

String

Environment type, defaults to process.env.NODE_ENV or development. Common values are development, staging and
production; however the applications are free to use any names.

[modelSources]

Array.<String>

List of directories where to look for files containing model definitions.

[middleware]

Object

Middleware configuration to use instead of {appRootDir}/middleware.json

[components]

Object

Component configuration to use instead of {appRootDir}/component-config.json

[mixinDirs]

Array.<String>

List of directories where to look for files containing model mixin definitions. All files (mixins) found
in these directory are loaded.

[mixinSources]

Array.<String>

List of directories where to look for files containing model mixin definitions. Only mixins used by
application models are loaded from these directories.